WASHINGTON—South Korea is pressing the Obama administration for U.S. permission to produce its own nuclear fuel, a move that nonproliferation experts said could trigger a wider nuclear-arms race in North Asia and the Middle East.

The negotiation between Seoul and Washington, though part of a broader, long-term civilian nuclear cooperation agreement, is taking place as nuclear pressures swell on both sides of the Korean peninsula.

North Korea has expanded its atomic-weapons capability in recent months. It announced Tuesday that it was reopening a reactor complex used to harvest weapons-grade plutonium. Those actions have fueled calls in South Korea for the government in Seoul to respond by developing its own atomic-weapons capability.

Northeast Asian specialist Alexandre Mansourov assesses the validity of North Korea's nuclear threat to the South and to the U.S.

South Korea's government has reassured Washington during the negotiations that it isn't seeking to develop the ability to build nuclear weapons. "This government has no intention at all of pursuing nuclear capabilities in terms of weapons," said a senior government official in Seoul.

But American lawmakers and proliferation experts are concerned that the technologies Seoul is seeking—the ability to enrich uranium and reprocess spent nuclear-reactor fuel—would provide it with the key technologies to produce the fissile materials for a bomb.

That capacity could further inflame tensions between the Koreas and risk sparking a broader arms race in Northeast Asia, potentially including Japan and Taiwan.

"Mutual animosities are feeding off each other on the Korean peninsula," said Tom Moore, who served for the past decade as the senior adviser on proliferation issues at the Senate Foreign Relations Committee. "South Korea has no economic or practical reasons to engage in these activities at this time."

U.S. negotiators fear that allowing South Korea to develop any of the requested technologies would have knock-on effects across the Middle East and Asia, where the U.S. has sought in recent years to seal deals that forbid countries from producing their own nuclear fuel. Jordan, Vietnam and Saudi Arabia could demand the same terms, and it would reinforce Iran's desire to continue with its nuclear program, these people worry.

"It could get to the point where you could no longer rely" on the current nonproliferation framework, said Mr. Moore, who is now with the Center for Strategic and International Studies in Washington.

ENLARGE

By as early as next month, according to officials briefed on the diplomacy, South Korea and the U.S. are seeking to conclude the renegotiation of a 1972 nuclear-cooperation pact under which the U.S. provides Seoul with nuclear fuel and technology.

South Korea, however, is seeking to significantly increase its own technological capabilities as part of the agreement, according to these officials, so it can enrich uranium and reprocess the spent fuel discharged from the country's fleet of 22 nuclear-power reactors.

South Korea said it needs to be able to enrich uranium on its own to provide a steady supply of nuclear fuel for these reactors. It also said it needs the ability to reprocess the spent fuel in order to better store the waste, which is expected to reach 10,000 tons by 2016.

"They are pushing hard for this reprocessing ability," said Sen. Bob Corker (R., Tenn.), who met with senior South Korean officials last week in Seoul, including President Park Geun-hye, who is planning a visit to Washington in May. "There is a lot of national pride in this."

Mr. Corker, the ranking Republican on the Senate Foreign Relations Committee, stressed that Ms. Park and other senior South Korean officials said their government has no desire to pursue atomic weapons.

ENLARGE

But he said he was struck by how many other South Korean politicians, including ruling party member Chung Mong-joon, said Seoul now needs to reconsider its long-standing pledge not to pursue an atomic bomb.

"For what it's worth, two-thirds of the population have said they'd like the country to have nuclear weapons," Mr. Corker said, referring to a recent South Korean poll.

Two opinion polls taken in the immediate aftermath of North Korea's third nuclear test, on Feb. 12 found over 60% support for nuclear weapons to be based in South Korea. Support levels are lower when the consequences of such a move are accounted for, including a potentially weakened alliance with the U.S.

The WSJ's Michael Arnold speaks with the Rand Corporation's Scott Harold about China's strategic interests in North Korea and what North Korea hopes to achieve by escalating regional tensions.

The Obama administration has staunchly opposed allowing countries seeking nuclear-cooperation with the U.S. to engage in enrichment or reprocessing, because either path could be used to create the fissile material required to create an atomic weapon.

North Korea has mastered both technologies, according to the United Nations nuclear watchdog, the International Atomic Energy Agency.

Both the Obama and George W. Bush administrations pressed the United Arab Emirates to agree to a nuclear-cooperation agreement in 2009 that explicitly forbids the Arab country to produce any of its own nuclear fuel.

President Barack Obama called the successful completion of the U.A.E. deal the "gold standard" for future U.S. nuclear-cooperation agreements. Washington has been seeking to replicate these same terms in negotiations it is currently engaged in with Seoul, Amman, Hanoi and Riyadh.

All of these capitals, however, have balked at agreeing to similarly rigorous terms, citing both economic and security reasons, according to U.S. officials who have taken part in the negotiations.

South Korea has argued that it shouldn't be wholly reliant on outside counties for the nuclear fuel that powers much of its electrical supply. South Korea has stressed that the reprocessing technology it is seeking to master, called pyro processing, is crucial to managing its growing nuclear waste, which could potentially pose an environmental threat.

South Korea says it will agree to extensive monitoring by the IAEA of all its nuclear sites to guard against any proliferation fears. Japan has a nuclear cooperation agreement with the U.S. dating back to the 1980s that allows Tokyo to reprocess the spent fuel from its nuclear reactors.

Pyongyang's Nuclear Program

South Korea politicians are also striking a nationalist tone, arguing that the U.S. shouldn't deny Seoul the same technologies that North Korea has acquired. Pyongyang kicked out IAEA inspectors in 2002 and pulled out of the U.N.'s nuclear Nonproliferation Treaty, which seeks to halt the spread of nuclear weapons.

On Tuesday, U.S. Secretary of State John Kerry met in Washington with his South Korean counterpart, Yun Byung Se, and discussed the nuclear-cooperation agreement.

But the top American diplomat and other U.S. officials have remained silent about the state of the negotiations.

South Korea's current nuclear pact with Washington expires in 2014, but U.S. and South Korean officials said the terms of a new deal would need to be agreed upon by June in order to gain congressional approval by year-end. South Korea is currently totally reliant on uranium imports to fuel its reactors, and between 20% and 30% comes from the U.S.

The U.S. has had a checkered history with South Korea on the issue of nuclear weapons.

Seoul formally renounced in 1992 the pursuit of atomic explosives in a declaration that called for the "denuclearization of the Korean Peninsula."

Just two years later, the Clinton administration threatened military strikes on the North when the U.S. and IAEA discovered that Pyongyang was diverting plutonium from its Yongbyon nuclear reactor for a secret atomic weapons program.

Seoul was caught by the U.S. pursuing a secret nuclear weapons program in the 1970s, under the leadership of Park Chung Hee, a general and the father of South Korea's current leader. Mr. Park was concerned about the calls by then-President Jimmy Carter for the U.S. to pull its remaining troops out of the Korean peninsula.

Similarly, Sen. Corker said he heard concerns from Ms. Park and other South Korean leaders about the long-term commitment of the U.S. to maintain a military presence in Asia, in part, because of Washington's fiscal issues. The lawmaker said this explained why some South Korean politicians believed Seoul needed to play a greater role in the country's defense.

"I assured her we will be there for them," Mr. Corker said of his meeting with South Korea's president.

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